The Beta Blocker Evaluation of Survival Trial (BEST) is a multicenter, collaborative clinical trial supported by the NIH and Veterans Administration assessing whether the addition of a beta blocker to standard therapy (digitalis, angiotensin converting enzyme inhibitor) will reduce mortality in patients with moderate to severe (NYHA Class III-IV) congestive heart failure (CHF) and left ventricular ejection fraction 2 35%. CHF is a major source of disability and death in the US and is increasing in prevalence as the population ages. Vasodilator therapy is the only intervention proven to reduce mortality. Increasing evidence suggests that elevated neurohormones in patients with CHF may hasten mortality, Preliminary data suggest that blunting the impact of neurohormones with beta blocker therapy may improve functional status, but there is no convincing evidence that beta blocker treatment improves longevity in patients with CHF. BEST, the largest trial of beta blockers in CHF to date, is seeking to randomize 2400 patients over 3 years at 90 US hospitals between an investigational beta blocker, bucindolol, and placebo. Primary endpoint is all-cause mortality. Secondary endpoints include cardiovascular mortality, quality of life, hospitalization and costs, ejection fraction at 3 and 12 months post- entry, incidence of myocardial infarction and need for other therapy, including cardiac transplantation.